Background: The mesenchymal stem cell-derived exosome (MSCs-exo) carrying microRNAs have been proved to regulate tumor biological activities. Clarifying molecular mechanism and identifying predictive microRNAs will be of great value in anti-tumor therapy improvement.
Objective: We aimed to investigate the regulatory role of microRNA-342-3p (miR-342-3p) in MSCs-exo on breast cancer.
Methods: Breast cancer tissues and cell lines were used to evaluate miR-342-3p expression in patients with or without lymph node/distal organ metastasis. The impact of MSCs-exo expression on tumor cell chemo-resistance and invasion/migration was measured. Dual-luciferase reporter gene assay was applied to identify binding site. Inhibitor of differentiation 4 (ID4) siRNA and miR-342-3p inhibitor transfection was conducted to further explore the miR-342-3p/ID4 axis on chemo-resistance and metastasis of breast cancer cells.
Results: Breast cancer cells revealed significantly lower level of miR-342-3p in patients with metastatic diseases. miR-342-3p suppressed invasive and chemo-resistant behavior of breast cancer tumor cells. Binding site between miR-342-3p and ID4 was proved. ID4 could reverse the influence of miR-342-3p on chemo-resistance. The tumor inhibition effect of IDA siRNA in vivo was also identified.
Conclusions: This study demonstrated that miR-342-3p acted as potential tumor suppressor by inhibiting metastasis and chemo-resistance of breast cancer cells through targeting ID4. This study might provide potential therapy targets for the treatment of breast cancer.
Keywords: Breast cancer; Chemo-resistance; ID4; Metastasis; miR-342-3p.
© 2021. The Author(s) under exclusive licence to The Genetics Society of Korea.